Simmer corn cobs and kombu in water for 10 minutes. Then remove cobs, add onion, carrot and celery. Simmer 10 minutes. Add the radishes and cook 10 minutes more. Either remove kombu, or cut into small strips and add back to the soup. Dissolve miso into a small amount of broth and add back to the soup. Slowly reheat for several minutes, but don't bring back to a full boil destroying miso's active enzymes. For a creamy texture, blend half in the blender. Garnish with parsley or chives.